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Ketone functionalization is a cornerstone of organic synthesis. Herein, we describe the development of an intermolecular C−H alkenylation of enamides with the feedstock chemical vinyl acetate to access diverse functionalized ketones. Enamides derived from various cyclic and acyclic ketones reacted efficiently, and a number of sensitive functional groups were tolerated. In this iridium‐catalyzed transformation, two structurally and electronically similar alkenes—enamide and vinyl acetate—underwent selective cross‐coupling through C−H activation. No reaction partner was used in large excess. The reaction is also pH‐ and redox‐neutral with HOAc as the only stoichiometric by‐product. Detailed experimental and computational studies revealed a reaction mechanism involving 1,2‐Ir‐C migratory insertion followed by syn‐β‐acetoxy elimination, which is different from that of previous vinyl acetate mediated C−H activation reactions. Finally, the alkenylation product can serve as a versatile intermediate to deliver a variety of structurally modified ketones. [ABSTRACT FROM AUTHOR]

Ketone functionalization is a cornerstone of organic synthesis. Herein, we describe the development of an intermolecular C−H alkenylation of enamides with the feedstock chemical vinyl acetate to access diverse functionalized ketones. Enamides derived from various cyclic and acyclic ketones reacted efficiently, and a number of sensitive functional groups were tolerated. In this iridium‐catalyzed transformation, two structurally and electronically similar alkenes—enamide and vinyl acetate—underwent selective cross‐coupling through C−H activation. No reaction partner was used in large excess. The reaction is also pH‐ and redox‐neutral with HOAc as the only stoichiometric by‐product. Detailed experimental and computational studies revealed a reaction mechanism involving 1,2‐Ir‐C migratory insertion followed by syn‐β‐acetoxy elimination, which is different from that of previous vinyl acetate mediated C−H activation reactions. Finally, the alkenylation product can serve as a versatile intermediate to deliver a variety of structurally modified ketones. [ABSTRACT FROM AUTHOR]

The discovery of safe, general, and practical procedures to prepare vinyl fluorides from readily available precursors remains a synthetic challenge. The metal‐free hydrofluorination of alkynes constitutes an attractive though elusive strategy for their preparation. Introduced here is an inexpensive and easily handled reagent that enables the development of simple and scalable protocols for the regioselective hydrofluorination of alkynes to access both the E and Z isomers of vinyl fluorides. These reaction conditions were suitable for a diverse collection of alkynes, including several highly functionalized pharmaceutical derivatives. Computational and experimental mechanistic studies support C−F bond formation through vinyl cation intermediates, with the E‐ and Z‐hydrofluorination products forming under kinetic and thermodynamic control, respectively. [ABSTRACT FROM AUTHOR]

The discovery of safe, general, and practical procedures to prepare vinyl fluorides from readily available precursors remains a synthetic challenge. The metal‐free hydrofluorination of alkynes constitutes an attractive though elusive strategy for their preparation. Introduced here is an inexpensive and easily handled reagent that enables the development of simple and scalable protocols for the regioselective hydrofluorination of alkynes to access both the E and Z isomers of vinyl fluorides. These reaction conditions were suitable for a diverse collection of alkynes, including several highly functionalized pharmaceutical derivatives. Computational and experimental mechanistic studies support C−F bond formation through vinyl cation intermediates, with the E‐ and Z‐hydrofluorination products forming under kinetic and thermodynamic control, respectively. [ABSTRACT FROM AUTHOR]

High throughput plant phenomics enables precise quantification of structural information for the complex crop canopy. Leaf to panicle ratio (LPR) in terms of light interception is a physiological trait we formerly developed to clarify the light distribution pattern within the canopy of japonica rice. Here, using the methodology of deep learning neural network (Transformer Feature Pyramid Network), we proposed a general method for LPR calculation for both japonica and indica rice, and tested it in the study on variation of canopy structure across nitrogen (N) fertilization modes. Field experiments over three years (2020–2022) with three nitrogen levels and two basal to topdressing ratios were conducted for two cultivars of each japonica and indica rice. Results showed contrasting dynamic variation of LPR between the two species, ascending for indica rice but descending for japonica rice along with the grain-filling progression. Indica rice had larger temporal variation in LPR than the japonica. N topdressing significantly increased the LPR of indica rice cultivars at same N level, whereas that of japonica was dependent on N level and genotype. Morphological measurement revealed that the differential response of LPR to N was associated with the height difference between the flag leaf and panicle, panicle curvature, leaf area index and panicle area index. Correlation analysis revealed that the relation between LPR and grain yield was significantly positive for indica rice but negative for japonica rice. Our findings suggest that LPR can effectively reflect the characteristics of canopy structure as affected by cultivars and fertilization modes, thus being a valuable physiological indicator for crop science. • LPR (leaf to panicle ratio) was used to compare the canopy structure between japonica and indica rice. • The two subspecies were contrasting in the dynamics of canopy structure. • LPR of indica rice was more sensitive to nitrogen topdressing. • LPR and yield was positively related for indica but negatively for japonica. [ABSTRACT FROM AUTHOR]

Herein, we describe an intermolecular direct branched‐selective α‐alkylation of cyclic ketones with simple alkenes as the alkylation agents. Through an enamine‐transition metal cooperative catalysis mode, the α‐alkylation is realized in an atom‐ and step‐economic manner with excellent branched selectivity for preparing β‐branched ketones. Employment of a pair of bulky Brønsted acid and base as additives is responsible for enhanced efficiency. Promising enantioselectivity (74 % ee) has been obtained. Experimental and computational mechanistic studies suggest that a pathway through alkene migratory insertion into the Ir−C bond followed by C−H reductive elimination is involved for the high branched selectivity. [ABSTRACT FROM AUTHOR]

Herein, we describe an intermolecular direct branched‐selective α‐alkylation of cyclic ketones with simple alkenes as the alkylation agents. Through an enamine‐transition metal cooperative catalysis mode, the α‐alkylation is realized in an atom‐ and step‐economic manner with excellent branched selectivity for preparing β‐branched ketones. Employment of a pair of bulky Brønsted acid and base as additives is responsible for enhanced efficiency. Promising enantioselectivity (74 % ee) has been obtained. Experimental and computational mechanistic studies suggest that a pathway through alkene migratory insertion into the Ir−C bond followed by C−H reductive elimination is involved for the high branched selectivity. An intermolecular direct branched‐selective α‐alkylation of cyclic ketones has been achieved using simple alkenes as the alkylation agents. 7‐Azaindoline is employed as a bifunctional ligand to facilitate enamine formation and guide subsequent C−H activation with an iridium catalyst. This method offers a straightforward and byproduct‐free means to access ketones with β‐stereocenters. [ABSTRACT FROM AUTHOR]

Selectivity control is a challenging and important subject in semihydrogenation of alkynes. Here, a combined theoretical and experimental study was performed to reveal the origin of the chemo- and stereoselectivity in cobalt-catalyzed stereodivergent semihydrogenation of alkynes. Three NNP and PNP type pincer ligands were considered in calculation. The computational results show that over-reduction of the alkene is forbidden in this catalytic system because the alkylcobalt(I) intermediate formed by alkene insertion prefers to undergo β -H elimination rather than protonation of the Co C bond. Distortion–interaction analysis along the reaction coordinate suggests that the higher distortion energy during methanol-mediated protonation of the alkylcobalt(I) species suppresses formation of the side product, thereby determined the chemoselectivity. Mechanistic investigation reveals that the active cobalt(I) hydride species formed by pre-catalyst [ C ] has strong catalytic activity for alkene isomerization. Subsequent control experiments combined with free energy comparison confirms this conclusion and reveals that fast deactivation of catalyst and the weaker reactivity of the cis-alkene intermediate in the presence of the alkyne substrate prevents Z / E alkene isomerization using pre-catalyst [ C ]. This results in the divergent stereoselectivity in the presence of different cobalt pincer complexes. [ABSTRACT FROM AUTHOR]

[Display omitted] • The minimum cumulative resistance model is used to quantify the trends of river ecological protection and construction expansion. • Spatial principal component analysis is used to determine the weights of the eight impact factors to assess river ecological risk. • The ecological risk assessed based on the 600 m buffer zone is the most sensitive and reflects the most detailed results. • The 765.51 km2 area in the study area has the potential to become a buffer zone for river ecological protection. • Constructing ecological networks is an effective measure to mitigate ecological risks and is more applicable to developing countries. The ecological risks associated with rapid urbanization have seriously undermined the river's ecological security. Especially for developing countries, the weak ecological foundation and enormous population pressure have increased the difficulty of river ecological protection. It is urgent to propose a bottom-line planning and management approach for river ecological protection in highly urbanized areas of developing countries. We quantified the minimum cumulative resistance of the river protection and construction land expansion processes. Then, based on the difference between these two minimum cumulative resistances, we assessed the river ecological risk in the Beijing plain area and presented a complete method to regional-level planning and management for river ecological protection. The results show that: 1) The spatial distribution of river ecological risks follows a three-tier ring structure, decreasing from the city center to the suburbs and then to the outer suburbs. The number of river segments with ecological risk levels 1, 2, and 3 are 44, 42, and 23, respectively, accounting for 39.2% of the total length of all river sections, which indicates that a larger number of rivers are facing high ecological risk. 2) The study area was divided into three zones according to the suitability of river ecological protection, with 2476.89, 765.51, and 3832.09 km2, respectively. Zone I and Zone II can be developed as protection nodes and riparian protection zones to develop the river ecological network in the central city. 3) We extracted 133 large ecological patches and 219 potential ecological corridors, which should be connected with the river network to enhance the connectivity of the local ecological landscape. The complete method proposed in this study is more focused and implementable to assist administrators in protecting and restoring the ecological security of urban rivers. [ABSTRACT FROM AUTHOR]

Although zinc catalysis is widely used in organic synthesis, very few studies on the dinuclear zinc mechanism have been reported. Here, a dinuclear zinc pathway is proposed for the Zn(OTf)2-catalyzed oxidative coupling of aldehydes with terminal alkynes. DFT calculations revealed that the deprotonation of the terminal alkyne would preferentially lead to the formation of a dinuclear zinc intermediate. The nucleophilic addition of this intermediate to an aldehyde, followed by an Oppenauer-type oxidation was investigated theoretically according to the mono- and dinuclear pathways. The formation of a dinuclear zinc intermediate from a mononuclear alkynyl zinc complex was exergonic, favoring the dinuclear zinc pathway. The subsequent protonation and regeneration of the active dinuclear catalyst were also evaluated by DFT calculations. The oxidizabilities of various aldehydes and ketones were evaluated to determine the best oxidant for this step. Trifluoroacetaldehyde was predicted to be a better oxidant for this reaction because its calculated energy barrier for the Oppenauer-type oxidation step was much lower than that of the other carbonyl complexes. [ABSTRACT FROM AUTHOR]

In this study, M11-L was used to evaluate the feasibility of the formation of rhodium(V) species using the rhodium(III)-catalyzed ortho-bromination of arenes as a model reaction. In most cases for these types of reactions, DFT calculations reveal that the bromination step involves a Br transfer from N-bromosuccinimide to the reacting arylrhodium to form a bromonium intermediate, followed by a Br shift to generate a new C−Br bond, which is more favorable than the previously proposed RhIII/RhV catalytic cycle. The rhodium catalyst remains in its +3 oxidation state throughout. The substituent effects of the reacting arene were studied, and computational results showed that the introduction of electron-donating groups on the reacting arene was favorable for this pathway. In contrast, the inclusion of a strong electron-withdrawing group on the aromatic ring would hinder the formation of a bromonium intermediate. Therefore, the RhIII/RhV catalytic cycle is favorable in cases that involve a RhV intermediate, which is generated by oxidative addition with NBS. In this pathway, the C−Br bond is formed by reductive elimination from the RhV intermediate. Additionally, a distortion-interaction analysis model along the reaction pathway was used to explain the directing-group effects. The results showed that the interaction energy controlled the reactivity because of the difference in electronic nature of various directing groups. [ABSTRACT FROM AUTHOR]

The first example of iron-catalyzed decarboxylative (4+1) cycloaddition reactions is described in this publication. By using this method, a wide range of functionalized indoline products were prepared from easily available vinyl benzoxazinanones and sulfur ylides in high yields and selectivities. A possible reaction pathway involving an allylic iron intermediate is discussed based on a series of control experiments and density-functional theory calculations. [ABSTRACT FROM AUTHOR]

The first example of iron-catalyzed decarboxylative (4+1) cycloaddition reactions is described in this publication. By using this method, a wide range of functionalized indoline products were prepared from easily available vinyl benzoxazinanones and sulfur ylides in high yields and selectivities. A possible reaction pathway involving an allylic iron intermediate is discussed based on a series of control experiments and density-functional theory calculations. [ABSTRACT FROM AUTHOR]

Methods that can simultaneously install multiple different functional groups to heteroarenes via C−H functionalizations are valuable for complex molecule synthesis, which, however, remain challenging to realize. Here we report the development of vicinal di‐carbo‐functionalization of indoles in a site‐ and regioselective manner, enabled by the palladium/norbornene (Pd/NBE) cooperative catalysis. The reaction is initiated by the Pd(II)‐mediated C3‐metalation and specifically promoted by the C1‐substituted NBEs. The mild, scalable, and robust reaction conditions allow for a good substrate scope and excellent functional group tolerance. The resulting C2‐arylated C3‐alkenylated indoles can be converted to diverse synthetically useful scaffolds. The combined experimental and computational mechanistic study reveals the unique role of the C1‐substituted NBE in accelerating the turnover‐limiting oxidative addition step. [ABSTRACT FROM AUTHOR]

Methods that can simultaneously install multiple different functional groups to heteroarenes via C−H functionalizations are valuable for complex molecule synthesis, which, however, remain challenging to realize. Here we report the development of vicinal di‐carbo‐functionalization of indoles in a site‐ and regioselective manner, enabled by the palladium/norbornene (Pd/NBE) cooperative catalysis. The reaction is initiated by the Pd(II)‐mediated C3‐metalation and specifically promoted by the C1‐substituted NBEs. The mild, scalable, and robust reaction conditions allow for a good substrate scope and excellent functional group tolerance. The resulting C2‐arylated C3‐alkenylated indoles can be converted to diverse synthetically useful scaffolds. The combined experimental and computational mechanistic study reveals the unique role of the C1‐substituted NBE in accelerating the turnover‐limiting oxidative addition step. [ABSTRACT FROM AUTHOR]

Employing the oxidative coupling of phenylacetylene with benzaldehyde as a model reaction, a density functional theory (DFT) study combined with extended X-ray absorption fine structure (EXAFS) experiment was carried out to reveal the difference between dinuclear and mononuclear zinc mediated nucleophilic addition. Newly reported DFT method M11-L computed results suggest that the mononuclear zinc mediated pathway, in which nucleophilic addition occurs via a four-membered ring transition state, is unfavourable both thermodynamically and kinetically. The dinuclear zinc mechanism, which appropriately explains the experimental observations, involves a six-membered ring transition state for nucleophilic addition. Subsequent in situ EXAFS experiment confirmed the existence of dinuclear zinc active species. Moreover, frontier molecular orbital (FMO) analysis and distortion–interaction energy analysis along the whole reaction pathways have provided interpretations for the advantage of dinuclear zinc mediated nucleophilic addition. Consequently, we believe this dinuclear zinc pathway will open up a general consideration of the dinuclear zinc mechanism for nucleophilic additions. [ABSTRACT FROM AUTHOR]

A transition-metal-free formal decarboxylative coupling reaction between α-oxocarboxylates and α-bromoketones to synthesize 1,3-diketone derivatives is presented. In this reaction, a broad scope of substrates can be employed, and neither a metal-based reagent nor an additional base is required. DFT calculations reveal that this reaction proceeds through a coupling followed by decarboxylation mechanism and the α-bromoketone unprecedentedly serves as a nucleophile under neutral conditions. The rate-determining step is an unusual hydrogen-bond-assisted enolate formation by thermolysis. [ABSTRACT FROM AUTHOR]

A transition-metal-free formal decarboxylative coupling reaction between α-oxocarboxylates and α-bromoketones to synthesize 1,3-diketone derivatives is presented. In this reaction, a broad scope of substrates can be employed, and neither a metal-based reagent nor an additional base is required. DFT calculations reveal that this reaction proceeds through a coupling followed by decarboxylation mechanism and the α-bromoketone unprecedentedly serves as a nucleophile under neutral conditions. The rate-determining step is an unusual hydrogen-bond-assisted enolate formation by thermolysis. [ABSTRACT FROM AUTHOR]

Cancer chemotherapy induced neutropenia (CCIN) is one of the most common toxicity caused by cytotoxic anticancer agents. Despite granulocyte colony-stimulating factor (GCSF) is widely used in clinical practice, the infection and infection-related mortality rate is still high for lack of functionally mature neutrophils. Saikosaponin d (SSD) is one of the major bioactive constituents of Radix Bupleuri (RB), which exerts immune-modulatory properties. We explored the function of SSD in CCIN therapy, we found that SSD contributed to generate functional mature neutrophils which capable of fighting infection both in vitro and in vivo. Network pharmacology was employed to explore the mechanism, 61 signal pathways might play an important role in CCIN treatment. Western Blot was employed to further confirm the potential pathway involved. We found CBL-ERK1/2 pathway was activated by SSD, followed by upregulating PU.1 and CEBPβ expression and leading to neutrophil differentiation. Our findings suggest a natural regimen SSD which could regenerate microbicidal neutrophils to effectively reduce CCIN-associated infection via activating CBL-ERK1/2, providing a rationale for future therapeutic approaches. [ABSTRACT FROM AUTHOR]

High‐valent iron‐oxo species are one of the common intermediates in both biological and biomimetic catalytic oxidation reactions. Recently, hydrogen‐bonding (H‐bonding) has been proved to be critical in determining the selectivity and reactivity. However, few examples have been established for mechanistic insights into the H‐bonding effect. Moreover, intramolecular H‐bonding effect on both C‐H activation and oxygen atom transfer (OAT) reactions in synthetic porphyrin model system has not been investigated yet. In this study, a series of heme‐containing iron(IV)‐oxo porphyrin species with or without intramolecular H‐bonding are synthesized and characterized. Kinetic studies revealed that intramolecular H‐bonding can significantly enhance the reactivity of iron(IV)‐oxo species in OAT, C‐H activation, and electron‐transfer reactions. This unprecedented unified H‐bonding effect is elucidated by theoretical calculations, which showed that intramolecular H‐bonding interactions lower the energy of the anti‐bonding orbital of iron(IV)‐oxo porphyrin species, resulting in the enhanced reactivities in oxidation reactions irrespective of the reaction type. To the best of the knowledge, this is the first extensive investigation on the intramolecular H‐bonding effect in heme system. The results show that H‐bonding interactions have a unified effect with iron(IV)‐oxo porphyrin species in all three investigated reactions. [ABSTRACT FROM AUTHOR]

The development of boron reagents is crucial for synthetic chemistry. Herein, we present a scalable and practical synthesis of diborodichloromethane (DBDCM) through the reaction of trichloromethyllithium with bis(pinacolato)diboron (B2pin2). The resulting DBDCM reagent serves as a basic synthetic unit for the construction of various structurally diverse gem‐diborylalkanes through controllable C−Cl functionalizations. Moreover, we have developed consecutive tetra‐functionalizations of DBDCM for the construction of diverse tertiary and quaternary carbon containing molecules. The use of isotopically enriched 13C‐chloroform and 10B2pin2 enables the synthesis of isotopically enriched 13C‐DBDCM and 10B‐DBDCM reagents, which are beneficial for the convenient synthesis of carbon‐13 and boron‐10 molecules. [ABSTRACT FROM AUTHOR]

The development of boron reagents is crucial for synthetic chemistry. Herein, we present a scalable and practical synthesis of diborodichloromethane (DBDCM) through the reaction of trichloromethyllithium with bis(pinacolato)diboron (B2pin2). The resulting DBDCM reagent serves as a basic synthetic unit for the construction of various structurally diverse gem‐diborylalkanes through controllable C−Cl functionalizations. Moreover, we have developed consecutive tetra‐functionalizations of DBDCM for the construction of diverse tertiary and quaternary carbon containing molecules. The use of isotopically enriched 13C‐chloroform and 10B2pin2 enables the synthesis of isotopically enriched 13C‐DBDCM and 10B‐DBDCM reagents, which are beneficial for the convenient synthesis of carbon‐13 and boron‐10 molecules. [ABSTRACT FROM AUTHOR]

Iron-catalyzed decarboxylative [4 + 1] cycloaddition reactions are described for the first time. [ABSTRACT FROM AUTHOR]

The article presents chemical equations for the article "Transition-Metal-Free Formal Decarboxylative Coupling of α-Oxocarboxylates with α-Bromoketones under Neutral Conditions: A Simple Access to 1,3-Diketones" by the authors, published in journal "Angewandte Chemie International Edition" in 2015.

Density functional theory (DFT) calculation has been used to reveal the mechanism of Pd-catalyzed disilylation of carbene, which is a pathway to construct disilylmethane derivatives. The DFT calculations indicate that the reaction starts with carbenation of a Pd(0) catalyst. Oxidative addition of disilane can then generate a carbene-coordinated disilylpalladium intermediate. Carbene insertion into the Pd–Si bond followed by reductive elimination gives the disilylmethane product and regenerates the Pd(0) catalyst with the formation of two C–Si bonds. The rate-determining step of this reaction is the carbenation step. The computational results show that the phosphine ligand is unfavorable for this type of reaction because of its high dissociation energy. In this type of reaction, a smaller substrate is favorable for the oxidative addition step because the weaker steric repulsion leads to a lower activation free energy of the oxidative addition step. The computational results also reveal that the reactivity of digermane and distannane is higher than that of disilane, which can be attributed to their low bond dissociation energies. [ABSTRACT FROM AUTHOR]

Precisely introducing two similar functional groups into bulk chemical alkenes represents a formidable route to complex molecules. Especially, the selective activation of two electrophiles is in crucial demand, yet challenging for cross‐electrophile‐coupling. Herein, we demonstrate a redox‐mediated electrolysis, in which aryl nitriles are both aryl radical precursors and redox‐mediators, enables an intermolecular alkene 1,2‐diarylation with a remarkable regioselectivity, thereby avoiding the involvement of transition‐metal catalysts. This transformation utilizes cyanoarene radical anions for activating various aryl halides (including iodides, bromides, and even chlorides) and affords 1,2‐diarylation adducts in up to 83 % yield and >20 : 1 regioselectivity with more than 80 examples, providing a feasible approach to complex bibenzyl derivatives. [ABSTRACT FROM AUTHOR]

Precisely introducing two similar functional groups into bulk chemical alkenes represents a formidable route to complex molecules. Especially, the selective activation of two electrophiles is in crucial demand, yet challenging for cross‐electrophile‐coupling. Herein, we demonstrate a redox‐mediated electrolysis, in which aryl nitriles are both aryl radical precursors and redox‐mediators, enables an intermolecular alkene 1,2‐diarylation with a remarkable regioselectivity, thereby avoiding the involvement of transition‐metal catalysts. This transformation utilizes cyanoarene radical anions for activating various aryl halides (including iodides, bromides, and even chlorides) and affords 1,2‐diarylation adducts in up to 83 % yield and >20 : 1 regioselectivity with more than 80 examples, providing a feasible approach to complex bibenzyl derivatives. [ABSTRACT FROM AUTHOR]

This paper explores whether the sponge city construction implemented in China can restore the hydrological condition of the river basins through runoff depth. The annual runoff depth was calculated based on the volume capture ratio of annual rainfall (VCRAR) and compared with undeveloped and before sponge city construction. The results conclude as follows: the current rainwater source control standard benefits the hydrology recovery in China. But the difference between before sponge city construction and undeveloped is large in 12.9% of the regions. The adjustment recommendations of the VCRAR proposed in this paper are favourable to restoring the river basin hydrology. [ABSTRACT FROM AUTHOR]

This report describes the unprecedented electrooxidation of a solvent (e.g. DMF)‐ligated B2cat2 complex, whereby a solvent‐stabilized boryl radical is formed via quasi‐homolytic cleavage of the B−B bond in a DMF‐ligated B2cat2 radical cation. Cyclic voltammetry and density functional theory provide evidence to support this novel B−B bond activation strategy. Furthermore, a strategy for the electrochemical gem‐diborylation of gem‐bromides via paired electrolysis is developed for the first time, affording a range of versatile gem‐diborylalkanes, which are widely used in synthetic society. Notably, this reaction approach is scalable, transition‐metal‐free, and requires no external activator. [ABSTRACT FROM AUTHOR]

This report describes the unprecedented electrooxidation of a solvent (e.g. DMF)‐ligated B2cat2 complex, whereby a solvent‐stabilized boryl radical is formed via quasi‐homolytic cleavage of the B−B bond in a DMF‐ligated B2cat2 radical cation. Cyclic voltammetry and density functional theory provide evidence to support this novel B−B bond activation strategy. Furthermore, a strategy for the electrochemical gem‐diborylation of gem‐bromides via paired electrolysis is developed for the first time, affording a range of versatile gem‐diborylalkanes, which are widely used in synthetic society. Notably, this reaction approach is scalable, transition‐metal‐free, and requires no external activator. [ABSTRACT FROM AUTHOR]

Building up new and efficient methods for the controlled conversion of carboxylic acids to aldehydes is important. Herein, we report a rapid, modular and scalable method for the conversion of carboxylic acids to aldehydes using pinacolborane at ambient temperature, in which a triflylpyridinium reagent is used. The conversion of carboxylic acid to intermediate acylpyridinium by triflylpyridinium is new. A binary pyridine‐coordinated boronium complex is generated after reduction. The unprecedented reduction of the acylpyridinium by HBpin opens up a practically direct synthesis of aldehydes from carboxylic acids. Theoretical studies indicate that the reduction of acylpyridinium requires a lower activation free energy than that of the product aldehyde. The synthetic advantage of this protocol is further highlighted by the scalable synthesis of aldehyde via continuous flow process. Configuration retention for chiral acids are presented in those syntheses. [ABSTRACT FROM AUTHOR]

Building up new and efficient methods for the controlled conversion of carboxylic acids to aldehydes is important. Herein, we report a rapid, modular and scalable method for the conversion of carboxylic acids to aldehydes using pinacolborane at ambient temperature, in which a triflylpyridinium reagent is used. The conversion of carboxylic acid to intermediate acylpyridinium by triflylpyridinium is new. A binary pyridine‐coordinated boronium complex is generated after reduction. The unprecedented reduction of the acylpyridinium by HBpin opens up a practically direct synthesis of aldehydes from carboxylic acids. Theoretical studies indicate that the reduction of acylpyridinium requires a lower activation free energy than that of the product aldehyde. The synthetic advantage of this protocol is further highlighted by the scalable synthesis of aldehyde via continuous flow process. Configuration retention for chiral acids are presented in those syntheses. [ABSTRACT FROM AUTHOR]

The development of a mild and general method for C(sp3)−H functionalization of cyclic amines has been an ongoing challenge. In this work, we describe the copper‐catalyzed enantioselective C(sp3)−H alkynylation of unactivated cyclic 2‐iodo‐benzamide under photo‐irradiation by intramolecular 1,5‐hydrogen atom transfer (HAT). The employment of a new bisoxazoline diphenylamine ligand, in conjunction with 1,1′‐bi‐2‐naphthol, which significantly improved the reduction potential of the copper complex, was the key to success of this chemistry. Mechanistic and computational studies supported that the new copper complex served the dual role as a photoredox and coupling catalyst, the reaction went through a radical process, and the intramolecular 1,5‐HAT process was involved in the rate‐limiting step. Apart from the broad substrate scope including unprecedented benzocyclic amines, this method also showed excellent diastereoselectivity in 2‐monosubstituted cyclic amines via substrate control. [ABSTRACT FROM AUTHOR]

The development of a mild and general method for C(sp3)−H functionalization of cyclic amines has been an ongoing challenge. In this work, we describe the copper‐catalyzed enantioselective C(sp3)−H alkynylation of unactivated cyclic 2‐iodo‐benzamide under photo‐irradiation by intramolecular 1,5‐hydrogen atom transfer (HAT). The employment of a new bisoxazoline diphenylamine ligand, in conjunction with 1,1′‐bi‐2‐naphthol, which significantly improved the reduction potential of the copper complex, was the key to success of this chemistry. Mechanistic and computational studies supported that the new copper complex served the dual role as a photoredox and coupling catalyst, the reaction went through a radical process, and the intramolecular 1,5‐HAT process was involved in the rate‐limiting step. Apart from the broad substrate scope including unprecedented benzocyclic amines, this method also showed excellent diastereoselectivity in 2‐monosubstituted cyclic amines via substrate control. [ABSTRACT FROM AUTHOR]

Stereoselective cyclopropanation reaction of alkenes is usually achieved by metal complexes via singlet‐metal‐carbene intermediates. However, previous transition‐metal‐catalyzed cyclopropanation of alkenes with acylsilanes afforded low diastereoselectivity. Herein, we report the first visible‐light‐induced transition‐metal‐free cyclopropanation reaction of terminal alkenes with trifluoroacetylsilanes and difluoroacetylsilanes. Both aromatic and aliphatic alkenes as well as electron‐deficient alkenes are suitable substrates for the highly cis‐selective [2+1] cyclization reaction. A combination of experimental and computational studies identified triplet carbenes as being key intermediates in this transformation. The gram scale reaction and late‐stage functionalization demonstrated the synthetic potential of this strategy. [ABSTRACT FROM AUTHOR]

Stereoselective cyclopropanation reaction of alkenes is usually achieved by metal complexes via singlet‐metal‐carbene intermediates. However, previous transition‐metal‐catalyzed cyclopropanation of alkenes with acylsilanes afforded low diastereoselectivity. Herein, we report the first visible‐light‐induced transition‐metal‐free cyclopropanation reaction of terminal alkenes with trifluoroacetylsilanes and difluoroacetylsilanes. Both aromatic and aliphatic alkenes as well as electron‐deficient alkenes are suitable substrates for the highly cis‐selective [2+1] cyclization reaction. A combination of experimental and computational studies identified triplet carbenes as being key intermediates in this transformation. The gram scale reaction and late‐stage functionalization demonstrated the synthetic potential of this strategy. [ABSTRACT FROM AUTHOR]

A transition-metal-assistedoxidative C(sp3)-H/N–Hcross-coupling reaction of N-alkoxyamides with aliphatichydrocarbons is described. During the reaction, nitrogen radicalswere generated from the oxidation of N-alkoxyamides.Experiments and DFT calculations revealed that transition-metal catalystcould lower the reactivity of the generated nitrogen radical by thecoordination of the transition metal, which allowed the selectiveradical/radical cross-coupling with the transient sp3carbonradical to construct C(sp3)–-N bonds. Various C(sp3)–H bonds could be transformed into C(sp3)–N bonds through this radical amidation strategy. [ABSTRACT FROM AUTHOR]

Cumulenes,including allene, ketenimine, and ketene, can be employedas dienophiles in Diels–Alder type reactions. The activationenergies of a Diels–Alder reaction between cyclopentadieneand either the CC bond or the other CX (X = C, N,or O) bond in cumulenes have been calculated by G3B3, CBS-QB3, M06-2X,and B3LYP methods. The reactivity trend for the CC bond incumulenes is allene > ketenimine > ketene and that of the CXbond in cumulenes is ketene > allene > ketenimine. Applicationofdistortion-interaction analysis only at transition states does notgive a satisfactory explanation for these reactivities. By employingdistortion-interaction analysis along reaction pathways, we foundthat the reactivity of the CC and CX bond in cumulenesis controlled by both of its distortion and interaction energies.The lowest distortion energy of allene leads to its highest reactivity;the higher interaction energy results in higher activation energyof ketene than that of ketenimine. Compared with the reactivity ofthe CX bond in cumulenes, the CO bond in ketene hasthe lowest activation energy to react with cyclopentadiene, due toits lowest interaction energy, whereas the lower distortion energyof ketenimine than that of allene leads to a higher reactivity. Thedistortion energy of the reactants can be attributed to folding abilityand molecule strain. The corresponding interaction energy of the reactantsis controlled by orbital interaction, closed-shell repulsion, andstatic repulsion. [ABSTRACT FROM AUTHOR]

Branch architecture provides crucial information for the understanding of plant trait variability and the adaptive strategies employed by trees in response to their environment. High-fidelity terrestrial laser scanning (TLS) data provide an accurate, efficient, and non-destructive means for constructing three-dimensional (3D) tree models and estimating architectural traits. However, the complex canopy structure of trees in natural forests and the presence of occlusion in TLS data pose significant challenges to achieving this goal. In this study, we present a novel algorithm, L 1 -Tree, for the construction of 3D tree models and the estimation of architectural traits from TLS data. This algorithm is grounded in the L 1 -Median algorithm and integrates a tree skeleton optimization procedure that considers the structural characteristics of tree branches. By comparing modeling results and manually derived branch traits for 24 trees of 24 species, we found that the L 1 -Tree algorithm achieved precision, recall, and F-score values of 0.94 for branch identification, coefficient of determination, root-mean-squared error, and normalized root-mean-squared error of 0.998, 0.068 m, and 0.3 % for branch length estimation, and a respective value of 0.958, 0.257 cm and 0.9 % for branch radius estimation. Additionally, the branch identification accuracy and accuracy in branch architectural trait estimation remained satisfactory across branch orders. Compared to established 3D tree model construction algorithms (e.g., TreeQSM), our L 1 -Tree algorithm demonstrated a superior capability in handling noisy environments and data gaps, making it a robust tool for TLS data-based tree architecture studies. Leaf-wood separation emerged as a crucial step influencing the performance of the L 1 -Tree algorithm. We observed significant drop in branch identification accuracy when using an automatic leaf-wood separation algorithm as input, highlighting the urgent need to develop effective leaf-wood separation algorithms to generate high-quality wood point clouds for tree architecture studies. • Proposed a novel L 1 -Tree algorithm for constructing 3D tree models from TLS data. • The algorithm achieved a high branch identification accuracy across branch orders. • The algorithm achieved a high branch architectural trait estimation accuracy. • The algorithm outperformed existing algorithms in handling noise and data gaps. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Mechanistic studies of the palladium catalyst activation with halide additives are of great importance to palladium catalysis. In this work, XAFS spectroscopy and cyclic voltammetry were utilized to study real structures of Pd(OAc)2 in solution with different inorganic halogen additives. XAFS results demonstrate that Pd maintained +2 in the presence of excessive LiCl, LiBr, ZnCl2, ZnBr2, and NaI. Fitting results of EXAFS spectra revealed that the Pd's first shell is replaced by halogen partially or completely depending on the halogen species. DFT calculations were conducted to identify the most reliable solvated structures. The combined experimental and computational studies elucidate the critical role of inorganic halide additives in Pd chemistry. [ABSTRACT FROM AUTHOR]

A new bifunctional ligand bearing chiral N‐heterocyclic carbene (NHC) and prolinol moieties is presented. Utilizing the designed ligand, an in situ formed Cu/Zn hetero‐bimetallic complex unlocks the asymmetric allylic alkylation reactions of allyl phosphates with zinc keto‐homoenolates, leading to the formation of various γ‐vinyl ketones with good regio‐ and enantio‐selectivity. DF sT calculation supports that the chelation of allyl phosphates with catalyst promotes the SN2' addition and the ligand‐substrate steric interactions account for the stereoselective outcome. [ABSTRACT FROM AUTHOR]

A method was developed for ketone synthesis via a photoredox‐assisted reductive acyl cross‐coupling (PARAC) using a nickel/photoredox dual‐catalyzed cross‐electrophile coupling of two different carboxylic acid esters. A variety of aryl, 1°, 2°, 3°‐alkyl 2‐pyridyl esters can act as acyl electrophiles while N‐(acyloxy)phthalimides (NHPI esters) act as 1°, 2°, 3°‐radical precursors. Our PARAC strategy provides an alternative and reliable way to synthesize various sterically congested 3°‐3°, 3°‐2°, and aryl‐3° ketones under mild and highly unified conditions, which have been otherwise difficult to access. The combined experimental and computational studies identified a Ni0/NiI/NiIII pathway for ketone formation. [ABSTRACT FROM AUTHOR]

A method was developed for ketone synthesis via a photoredox‐assisted reductive acyl cross‐coupling (PARAC) using a nickel/photoredox dual‐catalyzed cross‐electrophile coupling of two different carboxylic acid esters. A variety of aryl, 1°, 2°, 3°‐alkyl 2‐pyridyl esters can act as acyl electrophiles while N‐(acyloxy)phthalimides (NHPI esters) act as 1°, 2°, 3°‐radical precursors. Our PARAC strategy provides an alternative and reliable way to synthesize various sterically congested 3°‐3°, 3°‐2°, and aryl‐3° ketones under mild and highly unified conditions, which have been otherwise difficult to access. The combined experimental and computational studies identified a Ni0/NiI/NiIII pathway for ketone formation. [ABSTRACT FROM AUTHOR]

Several structurally diverse d‐mannose‐derived lactols, including various deoxy‐d‐mannoses and conformationally restricted bicyclic d‐mannoses, have been synthesized and investigated in mechanistic studies of β‐mannosylation through Cs2CO3‐mediated anomeric O‐alkylation. It was found that deoxy mannoses or conformationally restricted bicyclic d‐mannoses are not as reactive as their corresponding parent mannose. This type of β‐mannosylation proceeds efficiently when the C2‐OH is left free, and protection of that leads to inferior results. NMR studies of d‐mannose‐derived anomeric cesium alkoxides indicated the predominance of the equatorial β‐anomer after deprotonation. Reaction progress kinetic analysis suggested that monomeric cesium alkoxides be the key reactive species for alkylation with electrophiles. DFT calculations supported that oxygen atoms at C2, C3, and C6 of mannose promote the deprotonation of the anomeric hydroxyl group by Cs2CO3 and chelating interactions between Cs and these oxygen atoms favor the formation of equatorial anomeric alkoxides, leading to the highly β‐selective anomeric O‐alkylation. Based on experimental data and computational results, a revised mechanism for this β‐mannosylation is proposed. The utilization of this β‐mannosylation was demonstrated by an efficient synthesis of the hexasaccharide core of complex fucosylated N‐linked glycans. [ABSTRACT FROM AUTHOR]

In this work, we develop an oxidation-induced C–H functionalization strategy, which not only leads to a new avenue to build C–N bonds, but also leads to different site-selectivity compared with “classic directing-groups”. The high selectivity of our new catalytic system originates from the heterogeneous electron-density distribution of the radical cation species which are induced by single electron transfer between the aromatics and oxidant-Cu(ii) species. [ABSTRACT FROM AUTHOR]

A visible-light-driven radical-mediated strategy for the in situ generation of aza-ortho-quinone methides from 2-vinyl-substituted anilines and alkyl radical precursors is described. This process enables an efficient multicomponent reaction of 2-vinylanilines, halides, and sulfur ylides, and has a wide substrate scope and good functional group tolerance. Treatment of the cycloaddition products with a base leads to densely functionalized indoles in a single-flask operation. [ABSTRACT FROM AUTHOR]

A visible-light-driven radical-mediated strategy for the in situ generation of aza- ortho-quinone methides from 2-vinyl-substituted anilines and alkyl radical precursors is described. This process enables an efficient multicomponent reaction of 2-vinylanilines, halides, and sulfur ylides, and has a wide substrate scope and good functional group tolerance. Treatment of the cycloaddition products with a base leads to densely functionalized indoles in a single-flask operation. [ABSTRACT FROM AUTHOR]

In this study, we broke through the directing function of the amide group. The coordination interaction between metal and directing-group enhanced the reactivity of the substrate. Using this strategy, we realized the selective amination of 8-aminoquinolines at the C5 position via employing azoles as the source of amine. Various kinds of 8-aminoquinolines and different substituted azoles were compatible to afford the corresponding C–N coupling products. [ABSTRACT FROM AUTHOR]

A novel palladium-catalyzed aerobic (1+2) annulation was developed for the synthesis of 3-azabicyclo[3.1.0]hex-2-ene. The palladation of Csp3–H bonds took place twice at the same position in the whole reaction process. Preliminary mechanistic studies by in situ IR revealed that the second C–H palladation and reductive elimination might be slow steps. [ABSTRACT FROM AUTHOR]